1. Field of the Invention
The present invention relates to a high voltage direct current (DC) relay for hybrid vehicles or electric vehicles, and particularly, to an air-tight high voltage DC relay for hybrid vehicles or electric vehicles having an enhanced air-tight structure.
2. Background of the Invention
A hybrid vehicle accelerates using electric energy of a battery at an initial running of the vehicle and when reaching a predetermined driving speed, it moves by using an engine as a power source with blocking an electric power supply from the battery. Here, a high voltage direct-current (DC) relay is used for supplying or blocking the battery power. High voltage DC relays for the hybrid vehicles or electric vehicles are classified into a main relay and a sub relay. Typically, a gas-tight high voltage DC relay is widely used as the main relay, and a high voltage DC relay in the air is widely used as the sub relay. The main relay is configured by forming an arc extinguishing mechanism with a vacuum container made of ceramic, so it may less affect the usage environments. On the other hand, the sub relay is fabricated to be arc-extinguished in the air, so the operation reliability on the usage environment is important. Especially, since the operation reliability on usage environments of temperature and humidity is emphasized, a performance of maintaining an air-tight state is important for the high voltage DC relay in the air, accordingly, a method for maintaining the air-tightness is very important.
The present invention is to provide the high voltage DC relay in the air having an enhanced performance of maintaining an air-tight state, and a method for fabricating the same, in the high voltage DC relay in the air used as a sub relay for hybrid vehicles or electric vehicles.
Hereinafter, description will be given of a high voltage DC relay in the air and a fabrication method thereof according to the related art, with reference to FIG. 1.
The high voltage DC relay in the air according to the related art includes a molded case 1 in a box shape having one open surface, an actuator (e.g., see the reference numeral 2 of FIG. 2) accommodated within the molded case 1, and an arc extinguishing mechanism 3 installed on the actuator for covering the open surface of the molded case 1.
The high voltage DC relay in the air according to the related art can be assembled by accommodating the actuator within the molded case 1 with upwardly situating the open surface, and covering the open surface of the molded case 1 by laying the arc extinguishing mechanism 3 on the actuator.
Afterwards, for enhancing the air-tightness, a thermosetting resin 4 having high temperature is deposited thereon. While the thermosetting resin 4 is cooled to be hardened, an expanded air within the molded case 1 by the high temperature, is discharged, as indicated with an arrow in FIG. 2, into the external air via gaps formed at, for example, a boundary portion between the molded case 1 and the arc extinguishing mechanism 3, a portion near a stationary electrode, a portion near a coil terminal and the like.
Consequently, due to the gaps formed at those portions, the related art high voltage DC relay in the air cannot be maintained in the air-tight state. Furthermore, its operation reliability depends on the environmental variations of temperature and humidity, so the reliability cannot be ensured. Also, foreign materials such as dust or water can be introduced via the gaps.